Revolving crane accessory for fork trucks



Oct 1946- .1. R. WESTERVELT, JR

v REVOLVING CRANE ACCESSORY FOR FORK TRUCKS Filed April 7, 1944 2Sheets-Sheet l' J. R. WESTERVELT, JR 2,410,373

REVOLVING CRANE ACCESSORY FOR FORK- TRUCKS Filed April 7, 1944 2Sheets-Sheet 2 jiz 07 Patented Oct. 29, 1946 REVOLVING CRANE ACCESSORYFOR FORK TRUCKS John R. Westervelt, Jr., Duxbury, Mass, assignor toNational Fireworks, Inc., West Hanover, Mass, a corporation ofMassachusetts Application April 7, 1944, Serial No. 529,924

14. Claims. (Cl. 214-412) The subject-matter of the present invention isan accessory or attachment for fork trucks adapted for use tosuspend aload from the elevator of the truck and swing the load to either sidefrom a position in front of the truck.

Trucks of the character designated by the title fork trucks aredistinguished by an elevator guided to travel up and down on uprightguides suitably mounted on the truck, and provided with horizontaloutwardly projecting fingers or arms constituting a fork on which a loadmaybe placed for transportation. Such trucks are self-propelled, sometypes being provided with electric motors and storage batteries andothers with internal combustion engines, all suitably connected withdriving wheels. These trucks also have mechanisms under control of thedriver by which the elevator may be raised and lowered.

Trucks of this class are restricted in their scope of operations in thatthey re able to.pick up and deposit loads only in locations which can bereached by maneuvering the entire truck. Loads such as large cases,boxes and crates cannot be placed by a y type of fork truck in narrowspaces where there is not sufficient room to enable the truck towithdraw its fork from under the load by backing out. For instance, thespaces adjacent to the doorways of box cars cannot be fully loaded bythe use of fork trucks alone, even those trucks which have acomparatively short turning radius.

. The purpose of this invention is to provide an accessory for trucks ofthe character described by means of which loads may be swung to eitherside of the truck from a position in front of the truck, or vice versa.The novel features of the invention are embodied in a crane having abase which can be placed removably on the fork of a truck, an arm orboom supported on the base with capability of revolving through a'largeangle, such arm being adapted to suspend a load, and -motive means,manual or automatically driven under control of an operator, forswinging the boom throughout its arc of movement. The inventioncomprises a crane having the characteristics last mentioned, togetherwith auxiliary features described in the following specification; and itfurther comprises the combination of such a crane with a fork truck andthe elevator and fork thereof.

Drawings illustrating the invention are furnished herewith and in thesedrawings Figure 1, is a perspective view showing the forward end ofatruck and one embodiment ofmy novel crane separated from the fork ofthe truck but in position to be engaged therewith; and it shows bybroken line the elevator in a raised position with the crane support-edby the fork.

Figure 2 is a a rear elevation of the crane showing the drivingmechanism in section on line 2-2 of Figure 1. Figure 3 is a plan View ofthe crane showing by broken lines the extreme positions of its revolublearm or boom.

Figure 4 is a side elevation of the crane. Figure 5 is a detail crosssection taken on line 55 of Figure 3. Figure 6 i a fragmentary viewshowing an alternative type of driving mechanism for swinging the arm.

Like reference characters designate the same parts wherever they occurin all of the figures.

In Figure 1 the forward end of a fork truck is shown sufficiently toillustrate the salient characteristics of the elevator and fork thereof,without showing the operating details thereof. l0 represents the forwardend of the truck body and H represents one of the two wheels whichsupport the forward end of the body. The truck here represented is astandard electrically driven model carrying a storage electric batteryand having an electric driving motor. The battery box, drivers seat,steering wheel and control levers, by which the operation of the truckand of its elevator are controlled, have been omitted.

The forward end of the truck frame supports two upright guides l2 and 3with which a frame I4, constituting the elevator, is suitably engagedfor sliding movement up and down. The frame 14 carries massive forwardlyprojecting arms or fingers I5 which constitute the fork. An uprightcylinder I6 and piston rod l1 constitute part of the means for raisingand lowering the elevator. This and the balance of the means for thispurpose are all part of the standard equipment of fork trucks and needno further illustration here,

The crane comprises a massive and rigid base l8, preferably a heavy flatsteel plate, provided at the under side with channels l9 and 2!] toreceive the arms of the fork; said channels being conveniently made byplates '2 l, 22 and 23 welded to the base [8 and to each other. Theplates 23,

A'pivot or king bolt 24 is secured to the center secure the crane baseon the of the base l8. A spider consisting of a hub and arms 26surrounds and is rotatable about the pivot 24. The arms 26 carry ontheir outer ends hardened rollers 21 which rest on the flat uppersurface of the base and on which in turn rests a turntable 28 which iscentered by the pivot 24; Ther'ollers ,2l providean antifriction bearingfor the turntable.

It will be noted that the turntable is of disk form having a diametermore or less closely approximating the length and width dimensions ofthe base, that it is low in height and has plane upper and lowersurfaces, and that the rollers on the ends of the spider arms arerelatively near the circumference of the turntable. Thesecharacteristics have a number of advantages. They afford a stable andsubstantially frictionless support for the turntable, permit the use ofa simple and inexpensive antifriction bearing which needs no accuratelymade and accurately centered ball races, affords a broad support for thearm or boom, hereinafter described, and an extended surface for weldedunion with the boom, and its low height enables it, when elevated, topass through openings and into spaces bounded by low overheadstructures.

An arm or boom 2'9 is secured to the turntable. This boom isconveniently made of I beams 29 and 29a of which the flanges at one edgeare welded to the upper surface of the turntable in lines" parallel toand at equal distances from a diameter of the turntable. The" upperedges and flanges are braced and tied together by plates 30 and 3| whichare welded to them. On the outer end of the arm is secured a hooksupport composed of I beam sections 32 and. 33 and atop plate 34, weldedto each other and to the upper side. of the plate 3!); A hook 35 issuspended from the hook support just described, its shank being passedthrough the plate .34 and'a blocks3fr which bridges across between themembers 32 and is welded to them, and a nut 31 being threaded on the endof the shank and resting on the plate" 34. The extremity of the arm andof thehook support thereon are beveled, as shown in'Figure's 1 and-4,and the rear end of the hook support is additionally secured to the armby a U-shaped' rod' 38 constituting a strap which passes under thearmand the extremities of which pass through the plate 34 and carrynuts- 39' bearing on the upper surface of the plate. By reason of thebeveled formation; the hook is clear of the arm and may be turned withits entrance facing outward, as shown in the drawings, or in theoppositedirection. The length of the crane boom and distance of the hook fromthe pivot are governed by the capacity of the truck and the ability ofthe elevating mechanism to raise a heavy load supported from the end ofthe boom. By way of illustration, I may say that inthe particular modelillustrated here, the distance is 28 inches. It may be more or less inother models.

Mechanism is providedfor rotating the turntable 28' andtherebyswingingthe boom. One embodiment of this mechanism comprises a spur gear segment48 securedto the upper side of the turntable concentric with the pivot24, a pinion 4| meshing therewith", a reversible electric mot0rg42; aWorm 43'on the armature shaft of the motor, and a worm gear 45 securedto the shaft 46; to which the pinion 4| is also secured, and meshingwith worm 43. The motor is contained in a housing 41 secured to a gearcase 48 in which the worm and wheel gearing are containe and the gearcase is secured to the under side of a bracket 49 made fast, preferablyby welding, to the base structure of the crane. The gear segment 4!! issymmetrically disposed with respect 5 to the boom and extends far enoughto swing the boom more than 90 to either side from its mid position;that is, substantially as far as permitted by the guides 12 and 43 ofthe truck when the crane is operatively mounted on the fork of thetruck. The approximate limits of angular movement are indicated by thebroken line positions of the boom in Figure 3.

Fork trucks are commonly made with provisions for adjustment of the forkarms toward and from eachother, and the guide channels are located at adistance apart which is within the range of such adjustment and they arealso located as near as possible to the outside edges of the base plateto afford stability without undue strain. These guide channels are alsomade with dimensions closely approximating the cross section of the forkarms, but with suflicient clearance to permit easy entrance andwithdrawal of the arms. The bracket 49 is securedbetween the guideways,and the gear case and motor housing structure is suspended from thebracket in' a position where it will not interfere with the fork armswhen entered into the guide channels. When'not inuse', the crane base issupported from the floor on blocks or any other convenient stand ardwith the channels at a height between the limits of upward and downwardtravel of the fork; It may then be mounted on the fork by advancing thetruck so that the fork arms are entered into the guide channels-and byraising the elevator. Conversely the crane is disengaged from the truckby the action of lowering the raised elevator until the base of thecrane rests .on its supporting blocks or standard, and backing off thetruck.

When' the crane is thus assembled with an electric fork truck, the motor42 is connected with the battery'o'f the truck and with a reversingrelay and control switches by a 4-wire cable and detachable connectors.The controlling circuits of the motor include limit switches fifl and5|,

mounted on the base at opposite sides of the turntable and havingoperating arms 52 and 53 respectively. The turntable carries, in thelongi tudinal middle line of the boom, a switch-operating finger 54adapted to operate the limit switches; The arrangement of the switcharms and operating finger is such that the circuit of the motor isopened when the boom has swung 55 to nearly the limit of its rotarymovement to either side, their purpose of course being to preventoverrunning of the boom and causing the motor to stal1 or be damaged.The turntable may coast a few degrees after the motor circuit has beeninterrupted by either limit switch before the boom brings up against apositive stop. All of the electrical equipment, including the limitswitches, is or may be of standard make connected in circuits ofcharacter well known and understood by electricians and needs no furtherillustration'here. It is sufiicient for the pur-' pose of thisdisclosure that it be understood that the crane boom may. be revolved byautomatic means and is provided with means to prevent 7 overrunning andconsequent injury to the driv ing mechanism.

In situations where electric power is'not avail able; the turntable andboom may be rotated by manual power. An alternative driving means sooperable is shown in Figure 6, where a worm gear segment 40a issubstituted for the spur gear segment 40 and a worm 55 is arranged tomesh with the segment and is rotatable by a hand crank 56 secured to itsshaft. The shaft of the worm may be supported by bearings 51 secured tothe bracket 49, or otherwise, as desired. Moreover the worm 55'may bedriven by an electric motor instead of by the hand crank 56, which motormay be supported on the base by any suitable means clear of the forkguide channels. I

When the crane is assembled with the fork, as shown by broken lines inFigure 1, it is used in a raised position of the elevator to carryboxes, crates, or any other load suspended by slings engaged with thehook 35 and passing thence around and under the load, or by any othersuitable means; it being only necessary that the height of the load andits suspender be less collectively than the height to which'the cranehook may be lifted by the elevator of the truck. The load can be carriedby the' truck into a box car and deposited in a location at either sideof the path of the truck, as well as in other locations which could notbe reached by the fork, owing to obstructions limiting themaneuverability of the truck. Conversely loads in s'imilar positions canbe picked up with the aid of the crane and carried away by the truck.

What I claim and desire to secure by Letters Patent is:

l. The combination with a truck having an elevator and a fork carried bythe elevator, of a crane comprising a base separably engaged with andsupported by said fork, a disk-form turntable mounted rotatably on topof said base and supported by the upper surface thereof and a carrierarm or boom secured rigidly to the tumtable and projecting beyond theperiphery thereof.

2. The combination with a truckhaving an elevator and a fork comprisingseparated parallel arms projecting from the elevator, of a cranecomprising a base having guide channels in which said fork arms areremovably contained and by which the base is stably connected to thefork, a turntable supported on said base and adapted to rotate thereonabout a substantially vertical axis, an arm or boom secured to theturntable and protruding beyond the periphery thereon, and mechanismassociated with and reacting between said base and turntable forrotating the latter, constructed to prevent accidental rotation of theturntable.

3. A revolving crane for use with a fork truck, comprising a base havingmeans for separable interengaging connection with the fork of such atruck, a turntable mounted on top of said base and coupled therewith forrotary movement, and an arm or boom securedto said turntable in rigidunion therewith and projecting beyond the periphery thereof.

4. A revolving crane for use with a fork truck, comprising a base havingmeans for interengaging connection with the fork of such a truck, a

turntable mounted on top of said base and coupled therewith for rotarymovement, an antifriction bearing interposed between the turntable andbase, comprising a spider having arms radiating from the axis of theturntable and rollers on said arms resting on the flat top surface ofthe base and on which the flat under surface of the turntable rests, andan arm or boom secured to the turntable and projecting therefrom.

5. A revolving crane of the character and for the purpose set forth,comprising a base having guide channels for receiving the arms of atruck arranged to embrace and underlie the arms of such fork, aturntable supported on said base for rotary movement about asubstantially vertical axis, an arm secured to said turntable andprojecting laterally therefrom and a gearing between the base andturntable comprising a gear segment secured to one of them concentricwith the axis of rotation and a gear element carried by the other inmesh with said segment and adapted to be rotated.

7. A self-contained revolving crane comprising abase having provisionsfor interconnection with the fork of a fo-rktruck, a turntable mountedon said base to turn about a substantially vertical axis, an armsecuredto the turntable and projecting laterally therefrom, a gearsegment secured to the turntable concentric with the axis of rotation, agear element rotatably supported by the turntable in mesh with the gearsegment, and means mounted on said base for rotating said gear element.

8. A revolving crane comprising a base having provisions forinterconnection with the fork of a fork truck. a turntable mounted onsaid base to turn about a substantially vertical axis, an arm secured tothe turntable and projecting laterally therefrom, a gear segment securedto the turntable concentric with the axis of rotation, a gear elementrotatably supported by the tumtable in mesh with the gear segment. andan electric motor mounted on the base and operatively connected withsaid gear element to impart rotation thereto.

9. A revolving crane comprising a base having provisions forinterconnection with the fork of a fork truck, a turntable mounted onsaid base to turn about a substantially vertical axis, an arm secured tothe turntable and projecting laterally therefrom, a gear segment securedto the tumtable concentric with the axis of rotation. a gear elementrotatably supported by the turntable in mesh with the gear segment, anelectric motor mounted on the base and operatively connected with saidgear element to impart rotation thereto, and automatic means forstopping the motor when the turntable is rotated a predetermineddistance from a prescribed zero position.

10. A revolving crane comprising a massive base, members connected withthe under part of said base and with each other to form walls enclosingan open ended channel arranged to embrace and underlie an arm projectingfrom the elevator of a fork truck, a pivot rising from said base, aturntable having an extended upper surface engaged rotatably with saidpivot and supported on the base, an arm lying on the upper surface ofthe turntable in rigid union therewith projecting laterally from thecircumference thereof, and load sustaining means on said arm.

11. A revolving crane comprising a massive base, members connected withthe under side of said base arranged to form separate parallel channelsopen at one end and disposed to embrace and underlie parallel armsprojecting from the elevator of a fork truck, a bracket secured to thebase at; one boundary thereof' between saidchane nels; a I driving gearelement supportedby said bracket, arturntable supported on top of thebase in centralpivotal connection therewith,- an arm secured to saidturntable projecting laterally from thecircum-ference thereof, loadsustaining means on said arm; and a gear segment secured to the:turntable concentric with its pivotal axis in-rnesh with said'drivinggear element. I

; ;1- 2.--A revolving; crane comprising a base, a turntable in centralpivotal connection with the base having lateral dimensions substantiallycoextensive with those of the base and overlying the upper sidether'eoflan anti'friction bearing resting on'the top surface of the baseand on which the turntable rests, a'load-supporting armsecuredimmovably'to the turntable and projecting later'al-ly; therefrom; :and'members secured to the under'rside of the base forming the lateral andbottom Walls of channels adapted to receive the fork of a fork truck andto serve as a footing to support the crane on a floor or standard whenthe crane is-clear of the truck fork:

3--;"13;-A revolving crane foru'se with trucks of the fork truck typecomprising a base adapted to rest detachably on'the fork of a'f orktruck; and having channels oni-tsunder side bounded by walls arranged toembrace and extend; beneath the fork, a turntable supported on the toporsaid base in central pivotal connectiontherewith, agearseg mentsecured to said; turntable coaxial with: its

pivotydriving means for the turntable supported by thebase and includinga gear element in mesh with said segment; and a loadsu-pportingarmsecured to said turntable and projecting beyond the circumferencethereof. b

14. The combination with a truck having an elevator and a forkcomprising separated parallel arms projecting from the elevator, of acrane comprising a base having guide channelsjopenat one end in whichsaid fork arms are removably contained and by which the base is stablyconnected to the fork, thewalls of said channels embracing the fork armswith clearance sufiicient to permit easy entrance and withdrawal of thearms, a'turntable supported on the top surface of said base'and adaptedto rotatethereon about a sub stantially vertical axis, said turntablehavinga wide upper surface at a low level relatively tothe topsurface-of the base, and an arm or boom lying on the upper surface ofthe turntable in welded union therewith and protruding beyond theperiphery thereof.

- JOHN R; WES'IERVELT, JR.

